Process suspend() and resume() in call order

Source/modules/webaudio/AudioContext.cpp

 /*
  * Copyright (C) 2010, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1.  Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 133 matching lines @@
 AudioContext::~AudioContext()
 {
 #if DEBUG_AUDIONODE_REFERENCES
     fprintf(stderr, "%p: AudioContext::~AudioContext(): %u\n", this, m_contextId);
 #endif
     deferredTaskHandler().contextWillBeDestroyed();
     // AudioNodes keep a reference to their context, so there should be no way to be in the destructor if there are still AudioNodes around.
     ASSERT(!m_isInitialized);
     ASSERT(!m_activeSourceNodes.size());
     ASSERT(!m_finishedSourceHandlers.size());
-    ASSERT(!m_suspendResolvers.size());
     ASSERT(!m_isResolvingResumePromises);
     ASSERT(!m_resumeResolvers.size());
 }
 
 void AudioContext::initialize()
 {
     if (isInitialized())
         return;
 
     FFTFrame::initialize();
@@ skipping 586 matching lines @@
         return ScriptPromise::rejectWithDOMException(
             scriptState,
             DOMException::create(
                 InvalidAccessError,
                 "cannot suspend an OfflineAudioContext"));
     }
 
     RefPtrWillBeRawPtr<ScriptPromiseResolver> resolver = ScriptPromiseResolver::create(scriptState);
     ScriptPromise promise = resolver->promise();
 
-    // Save the resolver.  If the context is running, it will get resolved at the end of a rendering
-    // quantum.  Otherwise, resolve it now.
-    m_suspendResolvers.append(resolver);
+    if (m_contextState == Closed) {
+        resolver->reject(
+            DOMException::create(InvalidStateError, "Cannot suspend a context that has been closed"));
+    } else {
+        // Stop rendering now.
+        if (m_destinationNode)
+            stopRendering();
 
-    if (m_contextState != Running) {
-        // Context is not running so we can't wait for a rendering quantum to resolve the
-        // promise. Just resolve it now (along with any other pending suspend promises).
-        resolvePromisesForSuspendOnMainThread();

[haraken, 2015/05/18 14:47:59]

Actually I was wondering why we need to call
resolvePromisesForSuspendOnMainThread() whereas AudioContext::suspendContext()
is guaranteed to be executed in the main thread (see the ASSERT at line 747).

[Raymond Toy, 2015/05/18 18:25:08]

Yeah, I have no recollection of  why I did it this way.  Maybe to match how
resume works?

+        // Since we don't have any way of knowing when the hardware actually stops, we'll just
+        // resolve the promise now.
+        resolver->resolve();
     }
 
     return promise;
 }
 
 ScriptPromise AudioContext::resumeContext(ScriptState* scriptState)
 {
     ASSERT(isMainThread());
     AutoLocker locker(this);
 
@@ skipping 112 matching lines @@
     if (tryLock()) {
         // Take care of AudioNode tasks where the tryLock() failed previously.
         deferredTaskHandler().breakConnections();
 
         // Dynamically clean up nodes which are no longer needed.
         releaseFinishedSourceNodes();
 
         deferredTaskHandler().handleDeferredTasks();
         deferredTaskHandler().requestToDeleteHandlersOnMainThread();
 
-        resolvePromisesForSuspend();
-
         unlock();
     }
 }
 
 void AudioContext::resolvePromisesForResumeOnMainThread()
 {
     ASSERT(isMainThread());
     AutoLocker locker(this);
 
     for (auto& resolver : m_resumeResolvers) {
@@ skipping 17 matching lines @@
 
     // Resolve any pending promises created by resume(). Only do this if we haven't already started
     // resolving these promises. This gets called very often and it takes some time to resolve the
     // promises in the main thread.
     if (!m_isResolvingResumePromises && m_resumeResolvers.size() > 0) {
         m_isResolvingResumePromises = true;
         Platform::current()->mainThread()->postTask(FROM_HERE, threadSafeBind(&AudioContext::resolvePromisesForResumeOnMainThread, this));
     }
 }
 
-void AudioContext::resolvePromisesForSuspendOnMainThread()
-{
-    ASSERT(isMainThread());
-    AutoLocker locker(this);
-
-    // We can stop rendering now.
-    if (m_destinationNode)
-        stopRendering();
-
-    for (auto& resolver : m_suspendResolvers) {
-        if (m_contextState == Closed) {
-            resolver->reject(
-                DOMException::create(InvalidStateError, "Cannot suspend a context that has been closed"));
-        } else {
-            resolver->resolve();
-        }
-    }
-
-    m_suspendResolvers.clear();
-}
-
-void AudioContext::resolvePromisesForSuspend()
-{
-    // This runs inside the AudioContext's lock when handling pre-render tasks.
-    ASSERT(isAudioThread());
-    ASSERT(isGraphOwner());
-
-    // Resolve any pending promises created by suspend()
-    if (m_suspendResolvers.size() > 0)
-        Platform::current()->mainThread()->postTask(FROM_HERE, threadSafeBind(&AudioContext::resolvePromisesForSuspendOnMainThread, this));
-}
-
 void AudioContext::rejectPendingResolvers()
 {
     ASSERT(isMainThread());
 
-    // Audio context is closing down so reject any suspend or resume promises that are still
-    // pending.
-
-    for (auto& resolver : m_suspendResolvers) {
-        resolver->reject(DOMException::create(InvalidStateError, "Audio context is going away"));
-    }
-    m_suspendResolvers.clear();
+    // Audio context is closing down so reject any resume promises that are still pending.
 
     for (auto& resolver : m_resumeResolvers) {
         resolver->reject(DOMException::create(InvalidStateError, "Audio context is going away"));
     }
     m_resumeResolvers.clear();
     m_isResolvingResumePromises = false;
 }
 
 const AtomicString& AudioContext::interfaceName() const
 {
@@ skipping 63 matching lines @@
     visitor->trace(m_listener);
     // trace() can be called in AudioContext constructor, and
     // m_contextGraphMutex might be unavailable.
     if (m_didInitializeContextGraphMutex) {
         AutoLocker lock(this);
         visitor->trace(m_activeSourceNodes);
     } else {
         visitor->trace(m_activeSourceNodes);
     }
     visitor->trace(m_resumeResolvers);
+#if 0

[haraken, 2015/05/18 14:47:59]

You can remove this.

[Raymond Toy, 2015/05/18 18:25:08]

Oops.  Done

     visitor->trace(m_suspendResolvers);
+#endif
     RefCountedGarbageCollectedEventTargetWithInlineData<AudioContext>::trace(visitor);
     ActiveDOMObject::trace(visitor);
 }
 
 SecurityOrigin* AudioContext::securityOrigin() const
 {
     if (executionContext())
         return executionContext()->securityOrigin();
 
     return nullptr;
@@ skipping 24 matching lines @@
     // the destination node can GCed if JS has no references. stop() will also resolve the Promise
     // created here.
     stop();
 
     return promise;
 }
 
 } // namespace blink
 
 #endif // ENABLE(WEB_AUDIO)